Mount Rainier, also known as Tahoma, is a large active stratovolcano in the Cascade Range of the Pacific Northwest in the United States. The mountain is located in Mount Rainier National Park about 59 miles south-southeast of Seattle. With an officially recognized summit elevation of 14,410 ft at the Columbia Crest, it is the highest mountain in the U.S. …Mount Rainier, also known as Tahoma, is a large active stratovolcano in the Cascade Range of the Pacific Northwest in the United States. The mountain is located in Mount Rainier National Park about 59 miles south-southeast of Seattle. With an officially recognized summit elevation of 14,410 ft at the Columbia Crest, it is the highest mountain in the U.S. state of Washington, the most topographically prominent mountain in the contiguous United States, and the tallest in the Cascade Volcanic Arc.